Cutting device of a textile yarn during its feeding to an operating device

ABSTRACT

A device for cutting a textile yarn during its feed to an operator element such as a textile machine for its processing or a member for feeding it to such a machine. The device includes a blade member inserted into a housing presenting at least one aperture for passage of the yarn, the blade member carried by a movable support element subjected to an actuator for its movement. The movable support element being able to assume two working positions, a first position in which the blade member is spaced from the yarn and a second position in which the member cooperates with the yarn and cuts it. The actuator include a bistable electromagnet, a spring mounted about the movable support member urging the blade member into the cutting position.

The present invention relates to a textile yarn cutting device in accordance with the introduction to the main claim.

A textile yarn cutting device is known to be usually provided in the line feeding the yarn to an operator element, which can be an actual textile machine or a member which then feeds the yarn to such a machine. It usually comprises a blade member (or simply “blade”) associated with a support element subjected to actuator means which drive it (and with it the blade) within a casing housing the device. This latter comprises a portion in which the yarn slides during its feed. The support element is able to assume two working positions; in a first position this element maintains the blade spaced from the portion in which the yarn slides, and from the yarn itself, whereas in a second position this element brings the blade into contact with is the yarn to hence cut it.

Various types of such cutting devices are known: mechanical, air operated and electromagnetically operated. The mechanical devices comprise a spring associated with the support element and a clamp, internal to the housing, arranged to retain this latter in the first working position. This clamp is associated with an electromagnetically operated trigger; by operating the trigger the clamp is opened and the spring brings the support element into its second working position to hence achieve yarn cutting.

This mechanical device is of particularly large bulk and generally requires manual resetting.

With air operated devices the cutting device is controlled, together with its support element, by compressed air operated by a solenoid valve. This solution requires the presence of a compressed air circuit associated with the cutting device, this not always being available, and the possible addition of the solenoid valve to the cutting device if not already present therein.

Magnetic devices comprise a spring which acts on the support element to maintain it in its first working position. An electromagnet then brings this element into the second position to cut the yarn. This solution presents a very high electrical consumption related to the need to energize the electromagnet and maintain the support element in the cutting position (this consumption can become considerable in a textile machine having a plurality of cutting devices corresponding to the number of yarns worked).

U.S. Pat. No. 3,132,407 describes a cutting mechanism to be used in the textile field within a yarn cleaner used for removing slubs or other yarn irregularities. This known solution comprises electromagnetic circuit means having a pair of spaced-apart poles, a movable cutting member positioned in proximity to the material to be cut, and a permanent magnet arranged to move between the poles following activation of the electromagnet and operationally associated with said cutting member. When in its rest position, said magnet is in a position of minimum distance from one of these poles.

The use of a measurement capacitor is described, formed from conductive plates inserted in an insulating block with which the ferromagnetic poles of the magnetic circuit are associated. A yarn passes between these plates such as to vary the capacitance of the capacitor as a function of the variation is in yarn diameter. A control circuit measures the capacitance variation and provides a control signal at its terminals. This signal is applied to magnetic windings positioned about a metal member connecting the poles together. This creates opposing polarities in these latter, the result of which is a repulsion of the permanent magnet from one of these latter and its consequent movement with the associated cutting member. It hence acts on the yarn, which is cut.

This prior solution does not describe any spring urging the cutting member into contact with the yarn. Moreover in said US patent the force with which said cutting member acts on the yarn and the yarn cutting rate depend on the dimensions of the control electromagnet (defined by the two poles and by the metal member with the windings) of the cutting member. To achieve a high force and a high cutting rate the dimensions of this member are large, which however limits the use of said device in textile machines operating on hundreds of yarns.

CH699425 describes a device for cutting a yarn in a yarn cleaner which monitors and ensures yarn quality in spinning machines and winding machines in the textile industry. The device comprises an electromagnetic control member with a cylindrical moving coil, a movable solenoid member carrying a cutting element and a magnetic yoke, the coil, the movable member and the yoke being disposed such that the magnetic field generated by the control member closes through and returns via the control member and the yoke. A hole in the yoke for guiding and retaining the movable member and a part of this latter positioned within the hole have different shapes such that the space formed between them is not constant along the circumference of said member; this space is formed such that the magnetic field acting radially on the movable member is nullified. A spring is provided for returning the movable member to its rest position after cutting the yarn.

This prior patent enables the yoke and hence the device dimensions to be reduced, so saving space and enabling better use of the invention.

In addition a constant trust on the movable member is achieved, enabling high acceleration during the initial movement of the movable member and a shorter reaction time thereof.

Hence in this prior patent, the movement of the cutting element (associated with the movable member) is obtained only by virtue of the magnetic force developing within the described device. It follows that to increase the cutting force (for example on the basis of the yarn type on which it acts) the dimensions of those device parts generating the magnetic field (and the relative force) have to be increased, with consequent increase in the dimensions of the entire device described in the Swiss patent.

To this must also be added the need to increase the feed power to the device as its dimensions increase.

Because of this, said device is difficult to use on textile machines operating on several yarns.

Moreover the Swiss patent does not describe the use of a spring as a member for moving the cutting element, but only for returning this latter to its rest position after acting on the yarn (and spaced from it).

An object of the present invention is to provide a cutting device which represents an improvement compared with known solutions.

A particular object of the invention is to provide a cutting device of the stated type which is extremely compact and has a very low and virtually zero energy consumption.

Another object is to provide a device of the stated type which is extremely simple and of low cost.

A further object is to provide a device of the stated type which also enables e blade member to be automatically reset.

These and other objects which will be apparent to the expert of the art are attained by a cutting device in accordance with the accompanying claims.

The present invention will be more apparent from the accompanying drawings, which are provided by way of non-limiting example, and in which:

FIG. 1 is a view from above showing a device obtained in accordance with the invention;

FIG. 2 is a view from above showing a part of the device of FIG. 1;

FIGS. 3 and 4 are views from above showing the device of FIG. 1 in two different operating positions; and

FIG. 5 shows schematically a system for controlling a plurality of yarns to a textile machine comprising several devices according to the invention.

With reference to said figures, a device according to the invention is indicated overall by 1 and comprises a housing 2 comprising a base 3, lateral shoulders 4 and an end wall 5 connected to said shoulders at one of their ends 6 and carrying an anvil member 5A. In proximity to this latter, each shoulder comprises a recess 10, preferably provided with ceramic thread guides; the recesses 10 of the shoulders 4 are mutually parallel to hence be able to receive a yarn F fed to a textile machine or to another user element in a line feeding the yarn to said machine (such as a member feeding the yarn to this machine).

The base 3 presents holes 11 enabling the device 1 to be fixed by screws, rivets or the like (not shown) on a textile machine in a suitable position.

This base carries a bistable linear electromagnet 12 comprising an electromagnet 12A fixed to the inside of a U structure 13 fixed to said base in any known manner. This structure 13, which is metallic, presents in proximity to each of the free ends 14A of its parallel arms 14 (also parallel to the electromagnet 12), on a side thereof internal to the structure 13, a permanent magnet 16 positioned on the side of a cylindrical body 17 rigid with the bistable electromagnet and resting on a wall 18 rigid with the ends 14A of said arms. This wall is holed to enable passage of a support element 20 for a blade member or simply blade 21 fixed to a first end 22 of said movable element 20. The second end of this latter is inserted into the bistable magnet 12 and cooperates with its components, which are known and therefore not described.

A compression spring 25 is present on the element 20 between its widened first end 22 and the wall 18 (resting on the end 22 and the wall 18) to propel said element 20 from the wall 18 towards the anvil member 5A when the element 12 is suitably powered. This powering advantageously and preferably takes place under the control of a control unit (not shown) which enables said powering to take place via an electric feed cable 28. Direct current pulses are fed through this latter to power said electromagnet.

The element 20 is of non-magnetized magnetic material and carries the blade 21 fixed to its first end in any manner.

It will now be assumed that the device 1 is used in a line feeding yarn F to a textile machine or to a control member for this feed (or feeder).

When in the rest position (FIG. 3) or prior to the working position, the movable element 20 is maintained spaced from the wall 5 and from the anvil member 5A by the action of the magnetic field, generated by the permanent magnets 16, which closes at the element 20 via the structure 13.

Hence in practice the field generated by the permanent magnets 16 overcomes the (mechanical) spring force in order to maintain the movable element 20 in the first position without any current having to be applied to the electromagnet 12; all this is hence achieved without energy consumption with evident advantages when using a plurality of devices 1 in a textile machine operating on a correspondingly large plurality of yarns, such as a knitting machine.

By means of the permanent magnets a sort of magnetic trigger is hence achieved with can be activated by a small force (that generated by the electromagnet); in fact, on powering the electromagnet a large force is released (that generated by the spring) to obtain movement of the element 20 and the action of the of the blade 21 on the corresponding yarn.

In this respect, on feeding a current pulse to the electromagnet 12 through the cable 26, the magnetic force of the permanent magnets 16 is neutralized and the spring 25 moves the element 20 to propel it to strike against the wall 5. This movement brings the blade 21 into contact with the yarn F and to rest on the anvil member 5A, with consequent yarn cutting.

The use of the bistable linear electromagnet (defined by the magnet 12A, the structure 13 and the permanent magnets 16) enables a cutting device to be achieved which is of compact dimensions, simple and of quick action on the yarn. This enables its optimal use on textile machines operating on a large number of yarns, with each of which a corresponding cutting device can be associated. This is achieved by virtue of the compactness of each of these devices.

It should also be noted that devices with the same basic structure, comprising the electromagnet 12 (as aforestated) and with the same movable element 20 carrying the blade 21, can be used for acting on different yarns of different type and cross-section, by applying the necessary cutting force. This is easily achievable by using a spring 25 with a suitable elastic characteristic chosen on the basis of its use, the spring being the only member which moves the blade 21 towards the yarn and which defines the intervention force of this blade on the yarn.

In fact, as the device electromagnetic components operate only to release the movement of the element 20 (obtained by the action of the spring 25 interposed between the end 22 of this element and the wall 18) and do not participate in generating the thrust which moves the blade; this thrust is therefore totally related to the spring characteristics and is due only to the spring.

It is consequently possible to achieve extreme standardization of the “basic” device (with obvious benefits in terms of production costs), with the need only to select the suitable spring (with the necessary elastic characteristics) for the specific use and to mount this spring on the “basic” device (as aforedefined) to hence prepare it for this use.

In a first variant, the electromagnet makes it possible to be controlled such as not only to neutralize the field generated by the permanent magnets, but also to be added to said field in order to again reset the cutter, hence returning the movable element 20 from the cutting position to the rest position.

The device 1 can also be provided with an electronic circuit enabling it to communicate via a communication bus with a remote control unit or with sensors, also connected to the same bus. This control unit is able to control yarn feed by monitoring at least one of its characteristics, such as tension, velocity or shape.

The cutter can hence be activated not as the result of a direct electrical command, but as the result of a serial command or signal suitably fed by the control unit or by one of the sensors or control elements, a signal in which are specified the cutting command and the code associated with the particular cutter which is to operate.

In this case (see FIG. 5), a plurality of devices 1 and of other members 100 monitoring a yarn characteristic (such as yarn tension and/or feed velocity or sensors detecting any yarn imperfections or breakages) can be identified and defined by corresponding unequivocal identifying codes to hence create a feed control system for a plurality of yarns fed to the textile machine. These devices and monitoring members are connected to a field bus 110 and possibly connected to a control unit 120. Said sensors 100 and said control member 110 hence intervene on the devices 1 on the basis of the data obtained by these members and of the machine operation; by virtue of the code of the cutting devices 1 and of the monitoring members 100, this intervention is precise and enables only that yarn to be cut for which, for example, a feed abnormality is detected.

Other variants of the invention are further possible: for example, the element 20 could carry a blade 21 such as to retain the yarn after it has been cut. This enables the textile machine operation to be quickly resumed by intervening on the yarn (locked in the cutter and not free along the feed path), for example by re-knotting it to the end already beyond the cutter. These solutions are also to be considered as falling within the scope of the ensuing claims. 

1. A device for cutting a textile yarn during its feed to an operator element, said device comprising: a cutting blade member inserted into a housing presenting at least one aperture for passage of said yarn, said blade member carried by a movable support element subjected to actuator means for movement of the movable support element, said movable support element for assuming two working positions, a first position in which the blade member is spaced from the year and a second position in which said blade member impacts the yarn and cuts the yarn, the actuator means comprising a bistable electromagnetic actuator, the movable support element cooperating with a spring arranged to urge the blade member into the yarn cutting position after activation of the bistable electromagnetic actuator, said spring being interposed between a first end of said support element carrying the blade member and said electromagnetic actuator, wherein said electromagnetic actuator comprises an electromagnet inserted into a structure supporting at least one permanent magnet for retaining the movable support member in the first working position, the magnetic force retaining the support member in said first working position being nullified by the activation of the electromagnet to hence enable the spring to move the support member into the second working position.
 2. A device as claimed in claim 1, wherein said operator element comprises a textile machine for processing the textile yarn or a member for feeding the yarn to such a textile machine.
 3. A device as claimed in claim 1, wherein the spring is mounted about the support member, this support member having a second end inserted into the electromagnetic actuator.
 4. A device as claimed in claim 1, wherein the electromagnetic actuator is a bistable linear electromagnet.
 5. A device as claimed in claim 1, wherein the bistable electromagnetic actuator comprises a reversibly controllable electromagnet arranged to make the return movement of the support element from the second working position to the first reversible and automatic.
 6. A device as claimed in claim 1, wherein the blade member is arranged to retain the cut yarn within the housing after cutting the yarn.
 7. A device as claimed in claim 1, comprising an electronic circuit for connecting the device to a communication bus, said circuit containing an unequivocal identification code for identifying said device within the bus by said unequivocal code and to activate said device by serial command.
 8. A system for controlling the feed of at least one yarn to a textile machine, said system comprising: for said yarn at least one cutting device in accordance with claim 1, at least one member for monitoring a characteristic of said yarn, and a unit for controlling the yarn feed to said textile machine, wherein said device, said monitoring member and said control unit are connected via a serial line, said cutting device and member for monitoring having their own unequivocal identification code for being controlled and commanded individually by said unit, said command being a serial command.
 9. The system of claim 8, wherein the monitored characteristic of said yarn, is its tension, velocity or shape. 